Preface

Terrestrial plants, since their emergence, are subjected to harsh environ­

mental conditions that include hostile factors such as temperature extremes,

water deficit or excess, heavy metal toxicity, salinity, UV radiation, etc.

Owing to their sessile nature, plants need to confront such stresses, which

adversely affect their life cycle and their vital physiological processes like

seed germination, seedling growth, flowering, and seed production. There­

fore, it is not only necessary to understand the biochemical and molecular

mechanisms underpinning the defense responses, but also to come up with

effective strategies to mitigate stress-mediated toxicity and ensure better

yield. A lot of progress has been witnessed in understanding of the forward

and reverse genetic approaches and genome-wide analyses, especially in

model plants like the classical Arabidopsis thaliana and its extremophyte

relative Thellungiella salsuginea, both exhibiting multi-stress tolerance.

Traditional agronomic practices, including selection of tolerant cultivars,

fertilizer management, mutation breeding through radiation exposure, and

pre-treatment of seeds and seedlings before sowing, include some of the

effective adaptive strategies to fight against such stresses. The first rice

varieties, KT 20–74 and SH 30–21, released in China as early as 1957, were

developed through induced mutation. A semi-dwarf and non-lodging mutant

variety of wheat called Sharbati Sonora was generated through the treatment

of a red-grained Mexican variety, Sonora 60, by gamma radiation. Many

abiotic stress-tolerant crops, including varieties of rice, wheat, corn, potato,

soybean, cotton, and sugarcane, with superior yield, have been successfully

produced by mutation breeding and are being used for human consumption in

many countries. Priming of seeds and seedlings, viz., pre-exposure to water

and protective chemical agents, induces “stress memory” existing in both

the present generation and its offspring, and therefore appears as a prom­

ising strategy to cope with climate change and improve plant performance.

Various compounds like phytohormones, growth regulators, and signaling

molecules are induced during stress, each of which when used as a priming

agent, enables the plants to adapt against adverse situations. Stress memory

is highly epigenetic-based and involves diverse mechanisms, including

DNA methylation, histone modification, nucleosome positioning, chromatin

remodeling, and noncoding RNA-mediated regulation. Identification of